Leti Develops µLED Fabrication for High-Resolution Arrays

EuroPhotonicsJun 2017
Leti, a technology research institute at the French Alternative Energies and Atomic Energy Commission’s technology research unit (CEA Tech), has developed a µLED fabrication process to create high-resolution arrays at a 10-µm pitch.

The pixelization and its 873 × 500-resolution are designed for micro-display applications such as augmented-reality or virtual-reality tools and wearable devices. The blue or green GaN/InGaN µLED arrays use Leti’s proprietary self-aligned technology, which is key to achieving such a small pixel pitch. A combination of several damascene metallization steps are used to create a common cathode and expected to provide good thermal dissipation and prevent voltage drops within the micro-LED matrix. Electro-optical measurements showcase record efficiency and brightness exceeding requirements for device integration.

“Leti’s self-aligned process allows the creation of high-resolution µLED matrices with a reduced pixel pitch of 10 µm and paves the way toward even smaller pitches for next-generation devices,” said Ludovic Dupré, one of the authors of a paper describing the findings. “In addition, the use of the damascene metallization process of the cathode, which also is a new process developed at Leti, is a breakthrough compared to previous demonstrations of micro-LED matrices. The common cathode indeed fills the whole volume between the micro-LEDs and provides metallic spreading of electrical current between them, as well as thermal dissipation. These results are promising for integrating a micro-LED matrix in micro-display devices by hybridization on CMOS active matrices, and first prototypes are currently being tested.”

Leti is a developer of miniaturization technologies enabling smart, energy-efficient and secure solutions for industry.